Keep in mind that depending on your timezone, and where your username fits into the overall "vote fairy" batch, your vote reset time can be many hours (and many minutes) off from your local 12:00am midnight.

I, for example, seem to reset every night somewhere between 10:18pm and 10:28pm (I haven't pinpointed it exactly). That's Pacific Daylight Time. During Pacific Standard Time, it's an hour earlier for me. So if I use all my votes after 9:30pm, I won't have fresh votes again until the following night, after 9:20ish pm.